The most common and most likely answer to this crossword clue is the 8 letter word FILIGREE
I've seen this crossword clue in Independent
F
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L
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G
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Buddy explains!

The straight part
We know that "Ornamental lacework" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ornamental lacework = filigree.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does FILIGREE mean?
FILIGREE noun- A delicate and intricate ornamentation made from gold or silver (or sometimes other metal) twisted wire.
- A design resembling such intricate ornamentation.
- To decorate something with intricate ornamentation made from gold or silver twisted wire.